Telephone system



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ATTORNEY Oct. 22, 1935. G. v. KING TELEPHONE SYSTEM Filed May 22, 1954 9 Sheets-Sheet '7 @uw NSN .N .mi

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TELEPHONE SYSTEM Filed May 22; 1954 9 Sheets-Sheet 8 /N VEN TOR a. V. /f//VG ggz-@777% ATTORNEY 9 Sheets-.'SheerI 9 KING /NVE/y TOR G. V. /f/NG ATTORNEY TELEPHONE SYSTEM Filed May 22, 1954 Oct. 22, 1935.

Patented Oct. 22, 1935 UNITED STATES PATENT OFFICE Telephone Laboratories,

Incorporated, New

York, N. Y., a corporation of New York Application May 22, 1934, Serial No. 726,901

9 Claims. (Cl. 179-18) This invention relates to telephone systems and particularly to small capacity automatic telephone systems.

An object of the invention is to provide improved and economically arranged systems for automatically .establishing connections between telephone lines by means of switching units of the cross-bar type.

Heretofore systems have been provided in which connections may be established from any line to any other line in a single cross-bar switch through linking arrangements. A system of this kind has been shown in the patent to L. R.

Waller 1,567,309 of December 29, 1925. Other 1&5v systems have been provided where lines have been divided into groups in the same cross-bar which with linking arrangements having incoming or calling branches and outgoing or called branches appearing at each group whereby a calling line may be connected to a called line through an idle link. A system. of this kind is disclosed in the copending application of H. M. Bascom and O. A. Friend, filed October 7, 1933, Serial No.

693,676. In still other systems incoming lines have been arrange-d for connection with outgoing lines through cross-bar switches in such a manner that the .incoming lines are multipled to appear in groups in separate parts of a plurality of switches and with a different group of outgoing lines appearing in each switch. By this arrangement an incoming lline may be connected only to a particular group of outgoing lines. A

system of this kind has been disclosed in the patent to B. A. Betulander of June 16, 1925,

A feature of the present invention is a system using cross-bar switches with lines and linking arrangements of the general types .disclosed in the above mentioned systems and in which a f plurality of switches are arranged in divisions with one or more switches in each division depending upon the capacity of the systems. All lines are multipled to appear in each division and are arranged in groups in separate parts of the switches in each division and a single separate linking arrangement is provided for each division with a calling branch and a called branch appearing in each part of the switches in this division. Circuit means are provided whereby a calling line may be connected to a called line through an idle link and the associated division of switches, with the calling line connected directly to a calling branch and the called line connected directly to a called branch of this link.

The branches used for the connections are those that appear at the parts of the switches where the lines are located.

Another feature is an arrangement of this kind in which trunks may be multipled to appear in each division and arranged with the lines in the 5 groups in the separate parts of each division. Circuit means is'provided whereby a calling line may be connected to an idle trunk through an idle link. A calling line is in this case also connected to a calling branch of the link and the 10 trunk is connected to a called branch of the link. The branches used appear at the parts where the calling line and the idle trunk are located.

This invention has been illustrated in the accompanying drawings in which: l5

Figs. 1 to 9 show one embodiment of the invention with the circuit details complete for a portion of the lines and trunks only.

Fig. l0 shows the arrangement of Figs. 1 to 9 when reading the circuit; while Fig. 11 shows a 20 schematic of the general arrangement of the links and switches.

Cross-bar switches have been used which may be of any well known type in which the operation of a horizontal bar and a Vertical bar causes 25 contacts at the intersecting point to establish a connection between a calling line and a called line, a calling line and a trunk or a trunk and a called line through a link.

Referring now specially to the arrangement 30 shown in Fig. 11, the invention has been illustrated in connection with a system for ninety lines and from one to ten trunks making a total of one hundred connections. Four links have been shown l, 2, 3, and 4, although more links 35 may be used. Each link serves a division of switches, each division comprising two switches. The rst division comprises switches A and B, the second division comprises switches C and D,

the third, division comprises switches E and F 40- and the fourth vdivision comprises switches G and I. All the lines and trunks are multipled to appear in each division. The lines are arranged in groups GI to Gln in separate parts of the switches, groups GI to G5 appearing in switches 45 A, C, E and G in the four divisions and the groups G6 to GIU appear in switches B, D, F and I in the four divisions while one trunk appears in each group and is multipled from one switch to the other as indicated by the line 20 for group GI. 50 The trunks appear in the rst horizontal row of cross-connecting points and the lines appear in the remaining rows of nine horizontal crossconnecting points. The lines and trunks in each group are arranged to be connected to an in- 55 coming and an outgoing branch of the associated link. These branches are shown at 22 to 3| for the incoming branches and at 32 to 4| for the outgoing branches of the link I in the first division. Similar branches are provided for links 2 to 4 in the succeeding corresponding divisions as shown. Thus for each division comprising two switches, there appear ten groups of nine lines and one trunk in each group with an outgoing and an incoming branch of link I for each group. The lines and trunks may be numbered as shown in the iirst division. Connections may therefore be established from any subscribers line in any group to any other subscribers line in any group from any trunk to any subscribers line and from any subscribers line to any trunk. For example, if link I is idle and line II in group GI is calling line I6 in group G6, a connection is established from line I I to the branch 22 through the link I, through branch 31 to line I6 as indicated by a heavy line.

Referring now in general to the Figs. 1 to 9 arranged as shown in Fig. 10, a complete system of the arrangement shown in Fig. 11 has not been shown but only sufcient details to vclearly illustrate the working of the circuit in connection with link I. For example, in Figs. 7 and 8 only portions of the switches A and B has been shown. In switch A, portions of the group GI, G4 and G5 have been shown, While in switch B portions of the groups G6, and G|0 have been shown. In these groups mentioned only the contacts at the cross-connecting points of the lines appearing in the horizontal rows beginning with lines II, 6|, 3|, 4| and 5I and the trunks appearing in the upper horizontal row of the groups shown, that is for example in the lower horizontal row lines II, I4, I5, I6 and I0 appear and in the upper horizontal row trunks 0 I, 04, 05, 06 and 00 appear. To establish a connection through either of these switches, a magnet is provided for operating the horizontal bar corresponding to each row of lines and the row of trunks. These magnets corresponding to the rows mentioned have been shown and designated in switch A, 'II I, 16|, 13|, 14|, 15| and 10|, while in switch B the selecting magnets have been designated 8| 86|, 83|, 84|, 85| and 80|. These magnets may be called selecting magnets. A magnet is also provided for each vertical bar for the incoming branches and for each vertical bar for the outgoing branches. The magnets corresponding to the groups GI, G4, G5, G6 and GIO shown have been designated for the incoming branches 100, 104, 105, 106 and 1I0 and the magnets for the outgoing branches have been designated 800, 804, 805, 806 and 8|0. These magnets may be called holding magnets. 'Ihe operation of a selecting magnet and a holding magnet for an incoming branch establishes a connection between a calling line and this branch while the operation of a selecting magnet and a holding magnet of an outgoing branch establishes a connection between a called line and this branch. In Figs. 2, 3 and 4 have been shown partly completely and partly by the aid of dashdotted line boxes the subscribers line circuits for the lines II, I4, I5, I6, I0, I.54, 55.56 and 50. Corresponding equipments for trunks 0| and 04 have been shown. VIn various places throughout these drawings, circuits from the various lines to the switches A and B have been bunched and indicated by a single line and a bracket at each end. It should be noted that at each cross-point of the switches four connections may be made, three of which are the usual tip, ring and sleeve connections while the other is a supplementary connection wired in various ways depending on the type of connection Vas will be hereinafter described. In Fig. 4 besides the equipments for lines I0 and 50, there is shown a group of relays that are common to the lines or trunks in each horizontal row. In Figs. 5 and 6 there has been shown the relay equipment required for link I. In Fig. 9, certain connections and equipment have been shown for the remaining links 2, 3 and 4 enclosed in boxes that have been marked CD for link 2, and switches, EF for the third and GI for the fourth link and switches in the corresponding divisions, and in Fig. 1 has been shown relays common to all the links.

Referring now in general to the method of establishing connections by means of this system and the type of lines between which connections may be established; it should be understood that certain of the lines maybe single lines and others may be party lines. Of the party lines there may be two types, one having ten parties and another twenty parties on the line. Connections may be established from any line to any other line and the desired party on the called line may be called by means of an individual ringing code. Calls may also be established from any calling line to an idle trunk outgoing from the oice and calls may be received by this equipment over a trunk incoming to a line, whether a single subscribers line or a party line. Four digits must be dialed to establish ra connection from any line to any other line. The rst digit in case the call is intended for a single subscribers line or atenparty line, may consist of either two impulses or ve to nine impulses, asrthe system is arranged to make a first digit having one impulse ineffective. If a twenty-party line is called, the first digit must be either three or four impulses. If three impulses are dialed, preliminary selection takes place in the system of one set of ten parties on this line and if four impulses are dialed, pre-L liminary selections are made toy select the other set of ten parties on the line. The second digit may consist of any number of impulses from one to nine and the second digit being the tens digit selects the horizontal row of ten subscribers lines in which the desired subscribers line is located. 'Ifhe third digit which is the unit digit may consist of from one to ten impulses and selects the desired subscribers line in the horizontal row selected by the tenth digit, by selecting the vertical row in which this subscribers line is located. The fourth digit may consist of from one to ten impulses and selects the proper ringing code if a ten or twenty party line has been selected, while if a single party line has been selected the fourth digit will, of course, always be the same to select a code signal individual to single party lines. If the calling line desires a trunk connection a single `digit consisting of ten impulses must be dialed.

This will select the single horizontal row in which the trunks are terminated and trunk hunting for an idle trunk takes place automatically to connect the calling line with an idle trunk.

A description will now be made of the actual When a call is originated by the removal of the switch-hook at the subscribers station |I relay 20| is operated from battery through contacts of relay 202 over the ring conductor back over the subscribers loop and through the tip conductor, contacts of relay 202, winding of relay 20| to ground. The T, R and S leads are connected as shown by the conductors 200 to the contacts of the switch A at the cross-point for this line and the incoming branch 22 and outgoing branch 32 and multipled to corresponding cross-points of link I at all of the other links as indicated by the line 900. Relay 20| in operating connects ground to the lead TGI for the operation of relay 400 which with the relay 40| is common to all the lines in this horizontal row. This connection may be traced from battery and contacts of relay 402, left-hand winding of relay 000, lead TGI, contacts of relay 203, contact of relay 20| to ground. This causes the operation of relay 400 and relay 000 closes an obvious circuit for the operation of relay 40|. Relay 400 in operating closes a circuit vfor the operation of relay 402 from battery through the winding of relay 402, the right hand winding of relay 400 to ground at relay 202. Relay 002 in operating opens the circuit from battery through the left-hand winding of relay 400 so that these relays are now locked from this battery through the right-hand winding of relay 000. Relay 000 closes a connection to ground for the start lead ST for the operation of relays 00|, 602 and 603 in link I if this link is idle. The circmt for these relays may be traced from battery through the windings of these relays, contacts of relay 500, contacts of relay 530 and key 502, start lead ST to ground at relay 400. If link had been busy, this start lead connection from ground at relay 400 would have been transferredthrough the operation of relay 530 at the leithand armature and front contacts to the circuit through the key contacts of relay 902, to the lead 903 which leads to the relays in link 2 corresponding to relays 60|, 602 and 603 in link If link 2 is busy, the connection would have been transferred to the succeeding idle link. Relay 530 will be operated when link has been seized as will presently be described and lock its armatures in operated position by the hooked armature 503 of relay 504 to maintain it operated as long as the link is busy. When the link becomes idle, relay 504 will operate and release relay 530.

Relays 60|, 602 and 603 in operatingl cut through the TN leads 0 to 9 to the SM' leads to the ten selecting magnets of the switches A and B. Six selecting magnets of each switch have been shown. These connections are indicated by lead 125 and its brackets. One of these selecting magnets will be operated due to the horizontal row in which the calling line is located. As the calling line is located in the rst or lower row in the switch A, the selecting magnet 1|| will be operated over a circuit from battery through the winding of this magnet, lead 125, the No. l contact and armature of relay 503 and corresponding TN lead to ground at relay 400. The corresponding selecting magnet 8H will also be operated. This is immaterial in this case as the calling line is located in switch A. A connection is also established through the relays 60|, 602 and 603 for the holding magnets of the incoming branches of link for all the groups in switches A and B. However, the only one that will be operated is holding magnet 100. The circuit for this magnet may be traced from battery through its winding through the connection represented by lead 126, the corresponding holding leads HL, the No. 1 contact and armature of relay 003, the UI lead of group UE, armature andfront contact of relay 20|, an armature and back contact of relay 203, lead UGI of the group USI an armature and front contact of relay 40| and an armature and front contact of relay 403 to ground on the lead 401 at an armature and front contact of relay 602. The operation of these two magnets 1|| and 100 causes a connection to bev established at the cross connecting point'101 for the tip ring and sleeve conductors of the calling line II to the corresponding conductors of the branch 22 of link I. Relay 602 also closes a connection at its inner left-hand armature and front contact from the tip conductor of the incoming branch of the link over the lead 000, through a resistance to battery at the lower armature and front contact of relay 403. The battery over the lead 403 now aids in the operation of relay 50i as this relay is now also connected to the calling line in multiple with the line relay 20| in the calling subscribers line circuit and might not operate over the loop from the battery through contacts of relays 202 over the subscribers loop. The circuit for the operation of this relay 50| may be traced from battery, winding of relay 50|, contacts of relay 505, contacts of relay 506, the ring conductor of the incoming branch 22 oi link I, the ring connection at the cross-point 101, the ring conductor of the calling line over the calling subscribers loop, over the tip conductor, contacts of relay 202, winding of the line relay 20| to ground. The connection to the battery at contacts of relay 403 aids in the operation of this relay. Relay 50| in operating closes an obvious circuit for the operation of relay 500. Relay 501 is now also operated over the tip conductor from the battery on the lead 400 at the contacts of relay 403, contacts of relay 603 to the tip lead, and armature and back contact of relay 506, contacts of relay 505, winding of relay 501, contact of relay 604, to ground at the dial tone source at 605 (not shown). This connection from the dial tonesource 605 also extends through the cross-connecting point at 101 to the tip conductor of thek calling subscribers line to transmit dial tone to the calling subscriber to indicate that the circuit is ready for dialing.

In the meantime the operation of relay 500 opens the circuit for relays 60|, 602 and 603 at its outer left-hand armature and back contact and the release of these relays 60|, 602 and 603 opens the circuit for the selecting magnets 1|! and 816 so that these magnets are now released. While the holding magnet has closed a holding circuit for itself through its armature and front Contact, contacts of relay 509, contacts of relay 500 to ground. The holding magnet '|00 maintains the connection at 101 independent of the selecting magnet 1| Relay 500 now causes the operation of relay 508 from battery, winding of this relay, contacts of relay 602 contacts of relay 500 to ground. The operation of relay 508 closes a circuit for the operation of relay 509 from battery through the winding of this relay, contacts of relay 5|0, contacts of relay 503, makebefore-break contact of relay 509 to ground at an interrupter circuit connected at 53| (not shown). Relay 500 locks at its left-hand armature to ground and closes at one point a circuit for the operation of relay 5|2, from battery Ythrough the Winding of this relay, make-beforevfront contact in parallel with relay 509.

break contacts thereof through contacts -of relay 509 to a ground from an interrupter circuit at 53| (not shown) that will be supplied after a certain interval thereafter. When relay 512 operates it locked at its left hand armature and The purpose of these relays is to release the holding magnet after the lapse of this kinterval in case the calling subscriber does noty dial Within this period. It should be noted that relay7 530 is also operated by the operation of relay 508 to advance the star-t Wire for receiving on the next idle link ya succeeding call. This circuit 'may be traced from battery at the armature and back contact of relay 403, winding of 'relay 530 to ground at relay 508. It should be noted that relay -403 has released by this time due tothe release of relay 400 With relay 402 on the operation of relay 203 which takes place simultaneously with the operation of relay 53. The circuit for relay 203 may be traced from battery, left-hand Winding of this relay over the sleeve leads through the connection vat the cross-connecting point 101 to ground at relay 500. This causes the release of relays 400 and 402 which in turn causes the release of relay 403. Relay 530 in operating is locked lby the armature 503 of relay 504 to maintain the link busy and to transfer as stated the start lead to the next link.

Dialing for the desired subscribers line Will now take place. As hereinbefore stated the iirst digits determine the kind of party desired, whether a single, ten-party or twenty-party line.

In case of a single or ten-party line the iirst digit 'may be any digit except, 1, 3 and 4 and the operations caused by the first 'digit is the same in all cases. In the case of a twenty-party line the digits 3 or 4 should be dialed. The operation is then somewhat different. If now the calling subscriberdials, for example, the digit 6 to secure a connection to a single party line or a ten-party line the relay i501 is released at the beginning of the first impulse. Relay i501 may be -sloW-to-release and thus assist Yin `maintaining relay 500 operated during 'the pulsing. Therelease of relay 501 closes a circuit for relay V606 from battery, through the' Winding 'of this relay, contacts of relays 511 and 500`to ground at the left-hand armature and back contact of relay 501. Relay 606 closes an obvious circuit for `the operation of relay 601. These two relays remain operated during the 'pulsing asthey arerslow in releasing. Another relay operated by the release of relay 501 is th'e'relay 513 from battery, through the winding of this relay, contacts of relays .514,

V515, 501, 51| and 505 Vto 'ground at relay 1508.

`The operation of relay'513 closes -a circuit for the operation of ythe -rst selecting magnet 11-'1 and the companion selecting magnet '8151 .from'bal'f tery, selecting magnets 11 I, 0111 in parallel contacts of relay 609, contacts of relay 516, contacts of relay 513 to ground. YAt the end of the first impulse when relay 501 is again operatedfa circuit is closed for the operation of Yrelay 515 from battery, winding of relay 513, contacts of relay 514, contacts of relay 51'3,righthand winding of relay 515, contacts of relay 001 toground.` `Relay 515 in operating, closes an obvious circuit for the operation of 'relay 516 through its righthand Winding. Relay '.516 in :operating closes V'a locking circuit for selecting magnets 111 and 811, While relay 515 in operating opens the original energizing circiut for these imagnets. V0n the second' impulse when the .relay 501 is again released, acircut is close'dfor the operation :of

nrelay 514 .from battery, through the winding of this relay, left-hand Winding and contacts of relay 515 to the ground on relay 508 over the circuit hereinbefore described. Relay 514 in operating V'opens the circuit for relay 513 which now 5 releases to -close the circuit for the second selecting magnets, not shown, but whose energiz- Ving circuit is closed through the right-hand contacts of selecting magnet 111, lthrough contacts of relay 609, contacts of relay 5116 to ground at 10 contacts of relay 513. At the end ofthe second impulse, relay 501 is again operated causing the release of relays 515 and 514. The release of relay 515 closes a locking'circuit for the second selecting magnet through an inner left-hand ar- 15 mature and front contact of the second selecting magnet for .switch A, over a connection through the outer right-hand armature and back contact of relay 515 to ground at the outer left-hand armature and front contact of relay 516. Relay 2O 515 in releasing Aalso opens locking circuit for the first :selecting magnets 11 land 811. Relay 516 is maintainedoperated by relay 601 while the rst selecting magnet has released and the second selecting magnet is held operated. Dur- 25 .ing the succeeding impulses relays 513, 514 and 515 are operated alternately. That is, at the beginning of each odd impulse, relay 513 is operated and at the end of each odd impulse relay 515 is operated. At the beginning of each even 30 vimpulse relay 514 is Aoperated and relay 513 is released and at the nend of each even impulse relays 515 and 514 are released. Each impulse causes the operation of corresponding selecting magnets. In this case the sixth selecting magg 35 nets 161 and :861 are operated on the sixth impulse. This being an even impulse, relays 513, 514 .and 516 will be released at vthe end of the impulse. This is the end of the first digit. Relays 606 and 601 will also release. When relay 40 1606 releases and beforerelay 601 is released, both relays being slow in releasing, a circuit is momentarily closed for the operation of relay 608 .from battery, resistance 511, Winding of relay :60.8, `make-.before-break contacts of this relay, 45 'selecting magnet 811, contacts of relay 606 to groundiat contacts of relay 601. Relay 000 in operating closes a locking circuit for itself vthrough its left-hand armature and front contact, contacts of vrelay 510 to ground at relay 500. 60 When relay 601 releases, .relay 513 is operated dfrom battery, Vthrough resistance 519, Winding of lthis relay, contacts of relays 608 and 510 to ground at relay 508. It should be noted that as rlong as .the groundwas supplied `from relay 601, 55 relay 51;8 was short-circuited through the connection through its outer left-hand armature and back-contact to ground at relay 601. When relay.518 operates a circuit is closed for the opera,-

tion of relay 604 from battery, through the wind- G0 ing of thisrelay to ground at relay 518.

As .the holding circuit for relay 516 is opened -on thereleaseoi relay 601, .this relay in releasing opens the holding circuit for the .sixth selecting magnets whichare thereby released. Therefore, 05 thenet'result of the operation of the first digit is vto `energizeand lock relays 604, 608 and 518.

YNow when the second series of impulses is 'transmitted 4for the tenths digit selection, it Will be assumed that line 16 will be the called line. 70

Therefore, the tenths digit Will .be one impulse. The effect oftherelease of relay 501 is to cause lthe .operation of relays 513, '515 and 516 and to .provi'dean .operating Aand alocking .circuit for xt'hefzselectingmagnets-1:11 and `811, in vthesame 75 same time.

manner as hereinbefore described. At the' end of this impulse when relay 606 releases and before relay 601 is released, relay 608 will release as it is shunted by the ground connection from contacts of relay 601, through contacts of relays 606, 604 and 55B, through resistance 5I1 to battery. When relay 600 releases and the ground is still applied from relay 601 a holding circuit is provided for relay 5i@ through the make-beforebreak contacts of relay 608. It should be noted that relay 510 Was locked by the ground supplied through the left-hand armatures and front contacts of relay 508 when operated. This circuit may be traced from battery, resistance 5 I 9, wind- -ing of relay 5I8, make-before-break contacts of relay 608, contacts of relay 600, contacts of relay 606 to ground at contacts of relay 601. Relay 608 in releasing closes a circuit for relay 600 from battery, right-hand contacts of relay 606 to ground at contacts of relay 5I5. When the second impulse causes relay 501 to release relay 5I 4 operates and relay 5I3 releases and a circuit is closed for the second holding magnet of the group G2 over lead 1I2, contacts of magnet 800, lead 1I6, con- -tacts of relay 601, contacts of relay 5I6 to ground at contacts of relay 5I3. The circuit through the magnet can not be shown as this magnet is not shown. When the impulse ceases relay 5I5 releases and locks this second magnet over a circuit through its contacts to ground on leads and 121, through c-ontacts of relays 6I0, 5I3 and 516. However, the second holdingmagnet may not be directly operated from the second impulse, but an intermediate relay may be supplied to operate on the second impulse over the above mentioned path through lead 1I2. An arrangement of this kind will be explained further in connection with the operation of the sixth holding magnet 806. For the present it is suiiicient to say that the path for the operation of the third holding magnet is closed by this intermediate relay so that on the third impulse the third holding magnet will be operated directly and provide a path for the operation of a similar intermediate relay for the fourth holding magnet. As this intermediate relay has been shown at 803 the circuit may be traced as follows, bearing in mind that on the fourth impulse relays 5I3, 5I5 and 5M are released: Battery, Winding of relay 803, through `contacts of the third holding magnet (not shown) leads 1I9 and 1 I6, contacts of relays 600, 5I6 and 513. Relay 003 locks to ground at relay 5I6 over lead 12l. Holding magnet 804 does not operate as relay 006 is operated. The purpose of this arrangement is to prevent two succeeding holding magnets from being maintained operated at the When a succeeding holding magnet or succeeding relay is operated the preceding holding magnet or relay is released, thus preventing a momentary double connection winding of relay Gill, winding of relay 609, contacts of relay S00 to ground at contacts of relay 608. Relay 6I0 docs not operate in this circuit. As relays 5 I 3, 5 I 5 and 5 I 6 will release when relay 601 releases a holding circuit is now provided for the selecting magnets 1H and 8H in place of the holding circuit closed for these magnets when relay 5I5 operates. This circuit may be traced from battery, windings of magnets 1i I and 0I I, contacts of relay 609,

contacts of relay 6&0 to ground. When relay 601 r leases the locking circuit for relay 5 I8 is opened and relay 5 I 8 releases. The operation of relay 609 shifts the pulsing leads from the selecting magnets to the holding magnets.

The third or unit `digit may now be dialed. In

this case the unit digit is six impulses. The operations in dialing this digit are the same as hereinbefore described except that the holding magnets 800 and succeeding holding magnets or intermediate relays are operated and released in `5 succession until holding magnet 606 is operated to cause the connection to be established in the group of lines G5 at the cross-connecting' point 8I2 between the conductors 31 and the conductors of the called subscribers line I6. The operations are 10 as follows: The first impulse causes the release of relay 501 and this causes the operation of relays 606 and 601 as hereinbefore described. As the release of relay 501 causes the operation of relay 593 this relay now closes a circuit for the holding 15 magnet 800 in group GI. This circuit may be traced from battery, through the winding of magnet 800, contacts of relay 609, contacts of relay 5I6 to ground at the outer left-hand'armature and front contact of relay 5I3. At the end of this 20 impulse relay 501 is operated causing the operation of relay 5I5 and this relay causes the operation of relay 5I6. Relay 5I5 provides a locking circuit for magnet 800 from battery, winding of this magnet, its upper armature and front contact, 25

l to hold two succeeding holding magnets operated at the same time. The fth impulse causes the fifth holding magnet to operate, that is, the magnet 805 and the sixth impulse causes the intermediate relay 806 to operate in the same manner 30 Y as the intermediate relay 803. This relay in operating provides a locking circuit for itself through the lead 12 I to ground at contacts of relay 5 I ,6. As this is the last impulse the relays 601 and 606 would now release and also close a circuit for the 35 operation of the corresponding holding magnet 001. This circuit extends from battery, winding of magnet 801, contacts of relay 606 to ground at contacts of relay 601 and the magnet locks up over its armature and front contact to ground on lead 0 121 at relay 5I6. The calling line II is now connected to the called line I6 through the connections at the cross-connecting points 101 and 8I2. If the called subscribers line is busy a ground will be found on the sleeve lead which causes the 45 operation of the busy tone relay 520before 601 has released and after relay 606 releases at the end of the sixth digit. The circuit for this relay may be traced from battery through the winding of relay 520, normal contacts of relay 606, op- 50 erated contact of relay 601, contact of relay 52 I, sleeve lead to the called subscribers line through the cross-connecting point 8I2 of group G6. Relay 520 provides a locking circuit for itself over contacts of relays 505 and 5I0, to ground at re- 55 lay 508. Relay 520 provides a busy tone to the calling subscriber from the busy tone source connected to lead BT at 5I I, through contacts of relay 520 to the tip and ring conductors of the calling subscribers line over contacts of relay 52I 60 through condensers 522, 523, 524 and 525, contacts of relay 505, and 506, through the crossconnecting points 101. If, however, the called line is idle and when relay 606 releases and before relay 601 releases relay 608 again operates 65 over the circuit as hereinbefore traced. Relay 601 is thenreleased causing the operation of relay 5I0, which in turn causes the operation of relay 6I0 from battery, left-hand winding oi' this relay, contacts of relay 609, contacts of relay 5I6 10 tofground. It should be noted that the locking circuit through .the right hand winding of relay 6I0 short-circuits relay 609 which now releases. Relay 6I0 maintains the holding magnet 801 operated as this magnet was held from lead 12I 'Il which extended to ground at relay 6| 0. The holding circuit for selecting magnets 1| and 8| is openedby the operation of relay 6|0 and the circuits are now in condition for the transmission of the ringing code selecting digit.

Dialing for the proper ringing code may now take place. If the calling subscriber dials the digit l a particular code representing this digit will be transmitted to the called line which would be a single subscribers line. This particular code may also be used for calling .a single party on a single-party line or one of the parties on a tenparty line. Assuming that the code represented by one impulse is dialed, the iirst selec-ting magnets 1|| and 8|| will operate in the same manner as described in connection with the dialing of preceding digits. At the end of the impulse, when relay 501 is again operated, relays 5 I5 and 5||lare`oiperated in circuits as hereinbefore described.V The operation of relay 5|5 closes the locking circuit for magnets 1|| and 8| 'Ihen as relay 606 is released, relay 608 is released. This causes the operation of relay 5| from battery, winding of this relay, contacts oi relay 6|0, contacts of relay 608 to ground. Relay 5|| in operating Vprovides a` locking circuit for itself to ground-at relay 508 and for relays 5| 3 and 5|5 to maintain these relays operated after relay 601 releases, so that the holding circuits for magnets 1|| and 8|| will be maintained. The holding circuit completed by relay 5|| for these relays may be traced from battery, winding of relay 5|3, contacts of relay 5|4, contacts of relay 5|3, right-hand winding of relay 5| 5, contacts of relay 5| i, contacts of relay 5|0 to ground at contacts of relay 508. Relay 5|| .also closes a circuit for the operation of relay 521 from battery, winding of relay 521, contacts of relay 5| contacts of relay BIE and 6| 3 to ground at relay 5|5. 'I'hen relay 601 releases causing the release of relay 5| 8 and the operation of relay 52| from battery, winding of relay 52|, contacts of relay 601, contacts of relay 6|2, contacts or relay 520 to ground at contacts of relay 6|0. Relay 52| locks to the same ground directly. Relay 52| in operating closes a connection through from the called subscribers line to contacts of relay 526. Relay 526 is now operated due to the operation of relay 5| from the pick-up lead PU at the ringing interrupter terminating at 53| (not shown) over a Vcircuit from vbattery through the winding of this relay, contacts of relay 520, contact of relay 5| outer left-hand armature and back contact of relay 526 to the pick-up lead PU. Relay 526 in operating provides a locking circuit for itself thro-ugh a holding lead H of theV ringing interrupter at 53| through its outer-lefthand makebefore-break contacts andthe original circuit:

traced for this relay. When relay 526 operates the called subscribers line is extended to contacts of relay 521 and a circuit is completed for the transmission of theringing code from the rst code conductor in a group marked by the bracket 6M, that lead through the ringing interrupters (not shown)4 but controlled by the leads from the interrupter at 53|. The codes produced on the conductorsA in the group at 6M may consist of current impulses of different combinations such as long orY short impulses arranged 70 in d iierent numbers of impulses for each code as is well known in the The circuit for this ringing code may be traced from the lead in lthe group at 6M, contact of relay 6|5, contacts of selecting magnet 1||, contacts of relay 5H, left-hand armature and front contact of relay 521,

contacts of relay 526, contacts of relay 52 I, to the ring conductor of the called line over the crossconnecting point at 8|2, and back over the tip conductor through the connecting point 8 2, contacts of relays 52|, 526 and 521 to ground at the A lead G in the ringing interrupter connected at 53|. These ringing interruptor circuits may be so arranged that between each code transmitted,

, the ground on the holding lead H is removed to K cause the release of relay 526 and if the sublV scriber has not answered, the pick-up lead will again cause relay 526 to be operated to repeat the code. If the called subscriber answers when relay 526 is released, a connection is completed through the called subscribers loopy for the op- 1|!H eration of relay |0, from battery and ground through the windings of the relay 5|0 through contacts of relays 526 and 52| and the tip andV ring conductors over the calling subscribers loop,

causing the release'of relay 508 to dismiss the 20 time release circuit which was started to release the link after a certain interval if the subscriber failed to dial within that interval. Relays 5|3, 5|5 and 5|6 are also released. The release of re'- lay 5 5 causes the release of the selecting magnets 25 f When the calling subscriber hangs up his receiver, at the end of conversation, relay 50| is released causing the release of relays 500 and 508, causing the opening of the holding circuit for all relays operated and returns the circuits to normal. 40

In case of revertive calls, that is, if the called party is on the same line as the calling party, the calling party will receive the usual busy tone. As he knows that this is a revertive call, he will hang up and wait for the called party to be rung. In this case when the calling party hangs up, relays 501 and and 500 will release, but relay 508 will remain operated as on the release of relay 500 a circuit will be completed for the operation of relay 505, from battery, winding of 50 this relay, contacts of relays 500 and 5||, the fourth connection through cross-connecting point 128, as the connection has been established at this point to the same line as the called line, to ground at the fourth connection at cross-connecting point 101. The operation of relay 505 now establishes a new holding circuit for relay 508 to hold the connection until the called subscriber answers. This circuit may be traced from battery, winding of relay 508, contacts of relay 5|0, contacts of relay 505 to ground of relay 508. Now, when the called subscriber answers and relay 5|0 operates, relay 508 releases causing the release of the connection through the link. The calling and called subscribers may then converse over their own line.

Reference will now be made to the different operations when party lines are called. In regard to the ten-party lines the operations as stated are the saine as in the case of a single subscribers line but with a mino-r exception, namely that the parties are divided in two groups of five each on the line so that one set of ve parties must be rung with the codes on the tip conductor and the other set of ve parties must be rung with the Relay 520 opens the circuit for relay 30 codes on the ring conductor. It should be noted that in dialing an odd digit as the iirst digit, relay 5|5 is operated and in dialing an even digit this relay is not operated. Advantage is taken of this fact to distinguish between the two sets of rlve parties each on a ten-party line in calling. When relay 5I5 is operated a circuit is closed for relay tit. If relay 5|5 is operated due to the dialing of an odd digit a circuit will be closed for relay 521 when later relay 5|| is operated. This circuit may be traced from battery, winding of relay 521, contacts of relay 5| I, contacts of relays t l5 and 5I3 to a ground at relay 5I 5. In this case, therefore, theringing code will go out on the ring conductor to call one of the subscribers stations of the set of ve associated with this conductor. On the other hand, if an even number is dialed relay 5 I 5 is not operated consequently preventing relay 521 from operating so that the code selection will go out on the tip conductor.

In case the calling subscriber had desired a party on a twenty-party line and one of the parties of one set of ten parties of the desired twenty-party line he would have dialed digit '3 and if he had desired one of the parties on the other set of ten parties on this twenty-party line he would have dialed the digit 4. Assuming rst that he dials the digit 3. The operations will be the same as when he dials for a single or tenparty line with this exception that when the third selecting magnet 13| is operated and when relay 608 is operated, a. circuit is completed for the operation of relay 6|3 from battery, Winding of this relay, contacts of relays 604, 608, 13|, 601, lt and 513, to ground at contacts of relay 5|6. Relay 53 locks to ground at relay 508 through contacts of relay 5I0. This prevents relay 521 from operating when relay 5|I is operated which closes the circuit for relay 521 at another point at the end of thethird digit. Thus when the fourth digit is dialed the selected code on a lead l to i5 normally connected through contacts of relays 5|5 and SI5 is transmitted over the ring conductor to select one party out of a set of ten as determined by the dialing of the digit 3 as the rst digit. .On the other hand if the subscriber had dialed il as the first digit relay 6I3 is not operated but this has no effect as relay 521 Will not operate when relay 5|I is operated to close the circuit for the relay 521 at another point at the end of the third digit as the circuit for relay 521 is at that time opened at still another point by the operation of relay 6|5 which relay with relay 5|5 are operated at the end of the nrst digit when relay 508 operates. The circuit for these relays @I5 and BIG extends from battery, 'windings of these relays, contacts of relay 500 before it operates, contacts of relay 508 when it operates to ground supplied by the holding circuit for the fourth selecting magnet 14| from relay 555. These relays lock to ground at relay 555 through contacts of relay 5|0. Hence when the fourth digit is dialed a code Will be transmitted over one of the leads selected by the corresponding selecting magnet `from the corresponding leads Il to 20 connected by the operation of relay @l5 and 6|5 over the ring conductor to select one party out of the other set of ten as determined by the dialing of the digit 4 as the rst digit.

i the calling subscriber decides to make a connection to a distant office he Will dial the digit 0. In this case, the operations are the same as far as the calling subscriber seizing the incoming end of a link and dialing the digit 0 is relays 606 and 601 will release and cause the 5 operation of relays |508 and 5I6 as usual. The selecting magnet itl will in this case close a circuit for the operation o-f relay t`|1 from baty tery through the winding of this relay, contacts of selecting magnet 10|, contacts of relay 604 l0 to ground. This relay in turn closes a circuit for the operation of relay 6I2 from battery, contacts of relays 21 and 28, right-hand winding of relay 6I2 toi ground at contacts of relay SI1. Relay G|2 closes a substitute locking circuit for se- 15 lecting magnets 10| and 80| from battery through the winding of this magnet, contacts of relay SI2 to ground, as -the original locking circuits will later be opened due to the subsequent release of relays 601 and 5I5. Relay SI2 in op- 20 erating closes an obvious circuit for relay 28 which in turn closes a circuit for the operation of relay 21. As long as these two relays are operated no other relay corresponding to SI2 in any other link can operate to start hunting for 25 an idle trunk. The original energizing circuit for relay 6| 2 was opened on the operation of relays 21 and 28 but relay SI2 is locked in series with relay 28 to ground on .relay 621 which is held operated by a locking circuit 30 to ground at relay 508. Relay SI2 also operated relay SIS which connects the leads from each holding magnet to contacts of the cut-oft relay of the corresponding trunk. Assuming now that trunk 0| is idle its cut-o relay 206 will be re- 35 leased hence a circuit will be completed for the holding magnet 800. 'This holding magnet Will operate over a circuit from battery, through the Winding of this magnet through the rst armature and contact of relay GIB of the group marked 40 T through contacts of cut-olf relay 20B, contacts of relays BIE and 21 to ground at contacts of relay 28. Holding magnet 800 in operating provides a locking circuit for itself through its armature and front contacts, through contacts of 45' relay 606, to ground at contacts of relay 505' which latter relay is immediately operated when the connection is established between the trunk 0| and the subscribers line connected to this link at the cross-connecting point 1|1. The cir- 50 cuit for the operation of relay 506 may be traced from battery through the Winding of this relay, the lower contacts at the cross-connecting point 1|1 to ground. The ground connection established at the contacts of relay 508 for the sleeve 55 lead of the calling subscriber will now be extended through contacts of relay 550 and the sleeve contacts of the cross-connecting point 1|1, for the operation of the cut-on relay 206 from battery through its right-hand winding and ground over 60 the sleeve lead. Another effect of the seizure of the trunk 0I is that connections are made through means in the trunk for establishing a ground on the sleevelead from the trunk so as to hold the cut-on relay 206 operated after the 65 ground from the sleeve lead at relay 553 in the link is removed. This ground will also hold relay 506 operated from battery through its winding and inner left-hand armature and front contact, through the sleeve connection established at the cross-connecting point lil' over the sleeve lead to the trunk. This ground will also hold relay 203 operated after the ground is removed at relay 508 as it should be noted that when relay 500 is operated the connections over the tip 75 encumbrances.

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and ring conductors from the calling subscriber are disconnected from the connections through the relays 50| and 561 so that these relays will release and the tip and ring conductors are connected to the tip and ring conductors of the trunk. As relays 50i and 50'! will now release relays 506 and 508 will also release to remove the holding ground for the various relays operated at this time, that.. is, in this case relays 608, 5|8,

'612, 2l, 28 and 604. The release of relays 6|2,

2l and 28 permits another link to be used for trunk hunting as the battery is supplied at the right hand armature and back contact of relay 2l for the operation of the corresponding relay 6l2 in another trunk, such as, for example, relay 9I2 in link CD. The connection from the calling subscriber to the trunk will, as noted, now be extended through the link directly through the contacts of relay 506 without anyI The connection is held by the ground over the sleeve from the trunk and when this ground is removed relay 506 is released causing the release of the holding magnet 800 and when the calling subscriber releases the incoming branch or the link is disconnected by the release of the relay 203 and holding magnet 100.

If the call is incoming over a trunk for a subscriber in this exchange the seizure of the trunk, for example trunk I, causes the operation of relay 26%'. The operation of this relay closes a connection for the seizing of an idle link by causing the operation of the corresponding relays 406, 4t2 and 403 and a relay corresponding to 40i if there are more than four trunks. In this case the selecting magnets 10| and 80| Will be operated and the holding magnet 100 if the first link is idle so that the incoming connection will be established through the cross-connecting point H8. Otherwise the seizing of an incoming branch of an idle link is the same as when a subscriber seizes a link. The establishing of a connection to a desired subscrbers line fromj the trunk is identical with the establishing of a connection from a calling subscribers line to a called subscribers line in this exchange and therefore does not need any separate description.`

What is claimed is:

l. In a telephone system, a plurality of crossswitches arranged in divisions, lines multipled to appear in each division and arranged in groups in separate parts of each division a link for each division having a calling branch and a called branch appearing in each part of said division, and means for connecting a calling line to a called line through an idle link.

2. In a telephone system, a plurality of crossbar switches arranged in divisions of one or more switches in each division, lines multipled to appear in each division, and arranged in groups in separate parts of each division, a link for each division having a calling branch and a called branch appearing in each part of said division, and means for connecting a calling line to a called line through an idle link with the calling line connected directly to a calling branch or" said link and the called line connected directly to a called branch of said link.

3. In a telephone system, cross-bar switches, lines multipled to appear in all of said switches and arranged in groups in separate parts of said switches, a link flor each switch having a calling branch and a called branch appearing in each part of said switch, and means for connecting a calling line to a called line through an idle link.

4. In a telephone system, cross-bar switches, lines multipled to appear in all of said switches and arranged in groups in separate parts of said switches, a link for each switch having a calling branch and a called branch appearing in each part of said switch, and means for connecting a calling line to a called line through an idle link with the calling line connected directly to a calling branch of said link and the called line connected directly to a called branch of said link.

5. In a telephone system, cross-bar switches, v

lines multipled to appear in all of said switches and arranged in groups in separate parts of said switches, a link for each switch having a calling branch and a called branch appearing in each part of said switch, and means for connecting a calling line to a called line through a calling branch and a called branch of an idle link atthe parts of the associated switch where said lines appear.

6. In a telephone system, cross-bar switches arranged in divisions of equal numbers of switches in each division, lines multipled to appear in the switches of all divisions, and arranged in separate groups in separate parts of the switches, a link for each division of switches having a calling branch and a called branch appearing in each separate part ofthe associ-ated switches, and means for connecting a calling line to a called line directly through a calling branch and a called branch of an idle link at the parts of the associated switches Where said lines appear.

7. In a telephone system, a plurality of crossbar switches arranged in divisions, lines multipled to appear in each division and arranged in groups in separate parts of each division, trunks multipled to appear in each division, a link for each division, and means for connecting a calling line to an idle trunk through an idle link.

8. In a telephone system, a plurality of crossbar switches arranged in divisions, lines multipled to appear in each division and arranged in groups in separate parts of each division, trunks multipled to appear in each division and arranged in separate parts of each division, a link for each division havin-g a calling branch and a called branch appearing in all parts of said division, means for connecting a calling line to a called line through an idle link, and means for connecting a calling line to an 55 idle trunk through an idle link. n

9. In a telephone system, a plurality of crossbar switches arranged in divisions, lines multipled to appear in each division and arranged in groups in separate parts of said divis- 60.

ions, trunks multipled to appear in each division and arranged in separate parts of each division,

a link for each division having a calling branch and a called branch, appearing in each part of said division, means .for connecting a calling line to a called line through an idle link and means for connecting a calling line directly through a calling branch of an idle link and directly through a called trunk of said link to an idle branch, said connections being established at the parts of the associated switches where said calling line and said idle trunk appear.

GERALD V. KING. 

